iostream.py 文件源码

def _read_to_buffer(self):
        """Reads from the socket and appends the result to the read buffer.

        Returns the number of bytes read.  Returns 0 if there is nothing
        to read (i.e. the read returns EWOULDBLOCK or equivalent).  On
        error closes the socket and raises an exception.
        """
        while True:
            try:
                chunk = self.read_from_fd()
            except (socket.error, IOError, OSError) as e:
                if errno_from_exception(e) == errno.EINTR:
                    continue
                # ssl.SSLError is a subclass of socket.error
                if self._is_connreset(e):
                    # Treat ECONNRESET as a connection close rather than
                    # an error to minimize log spam  (the exception will
                    # be available on self.error for apps that care).
                    self.close(exc_info=True)
                    return
                self.close(exc_info=True)
                raise
            break
        if chunk is None:
            return 0
        self._read_buffer.append(chunk)
        self._read_buffer_size += len(chunk)
        if self._read_buffer_size > self.max_buffer_size:
            gen_log.error("Reached maximum read buffer size")
            self.close()
            raise StreamBufferFullError("Reached maximum read buffer size")
        return len(chunk)